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Birth intervals & uterine rupture aka how long to wait to VBAC

Suzanne recently left this comment in response to the article, I’m pregnant and want a VBAC, what do I do?

Hi. I’m new to your site and just trying to get some more info on VBAC. My daughter was a normal vaginal delivery. My second pregnancy(a surrogate pregnancy) was also a normal vaginal delivery. My third (also a surrogate pregnancy) was twins. I had planned to attempt a vaginal delivery with the twins with the support of my OB as long as Baby A was head down. Unfortunately she was breech and I ended up with a c-section at 36 1/2 weeks. My OB said if I want to attempt a VBAC for my next pregnancy I need to wait at least 2 years between the c-section and getting pregnant again. Is she just being cautious? Or is it really necessary to wait 2 years?

Suzanne,

I cover interbirth intervals in great detail in my class.  Here is a brief summary.

The short answer is: our limited evidence suggests that it’s probably better to have a 18-24 month interval between your cesarean birth and subsequent births.  It other words, it’s possibly best to wait 9 to 15 months after your cesarean to get pregnant.

Stamilio (2007) stated [emphasis mine], “We hypothesized that short interpregnancy intervals may lead to altered wound healing and an increased risk of uterine rupture in patients who attempt a vaginal birth after cesarean. Our hypothesis is based on previous observational studies that suggest an association between short birth interval and increased adverse perinatal outcomes and wound-healing research that indicates that uterine smooth muscle tissue repair evolves over several months…. Importantly, there is radiographic and hysteroscopic evidence that cesarean scar development is incomplete as long as 6 or 12 months postoperatively.

In other words, your scar is still healing and changing 6 to 12 months after your cesarean.

Stamilio (2007) found the rate of uterine rupture when women got pregnant less than 6 months after their cesarean to be 3.05%, which was three times higher than their average rate of 0.9%. That is a very high rate of rupture, but keep in mind two things.

First, they only had 286 women who got pregnant within 6 months of their cesarean and that is not a large enough population to measure uterine rupture which occurs about 0.4% of the time in spontaneous labors after one prior low transverse cesarean (Landon, 2004).   In order to accurately measure something that happens at that rate, we need about 5,000 women for that one category.

Second, 68% of those 286 women had their labors induced or augmented which we know increases the risk of rupture (Landon, 2004).

To read the abstract of this study, please go here and you can obtain a free PDF of the entire study here.

Stamilio (2007) as well as the other studies that have focused on uterine rupture by interpregnancy/interbirth intervals are rather small.  It will be nice if/when larger studies are conducted so we have a better idea of the risk differential, if any, between births occurring less than 18 months post cesarean versus more than 18 months.

I personally think it’s always a good idea to give your body plenty of time to heal and wait at least 9 months to get pregnant.

Does that mean that you should have a repeat cesarean if you get pregnant sooner?  I don’t think we have enough information right now to make that determination.

Also keep in mind that since you have two prior vaginal births, your likelihood of VBAC success increases to over 85% (Landon, 2005).

You can read more by looking through my bibliography.  Search for the terms ‘interbirth’ (time between cesarean birth and subsequent birth) and ‘interpregnacy’ (time between beginning of cesarean pregnancy and the beginning of subsequent pregnancies.)

Best of luck with your decision!

Warmly,

Jen

Stamilio, D. M., DeFranco, E., Pare, E., Odibo, A. O., Peipert, J. F., Allsworth, J. E., et al. (2007). Short Interpregnancy Interval: Risk of Uterine Rupture and Complications of Vaginal Birth After Cesarean Delivery. Obstetrics & Gynecology , 110 (5), 1075-1082.

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8 comments to Birth intervals & uterine rupture aka how long to wait to VBAC

  • tiffany

    Hi, i am on my second pregnancy, my first one was a csection. Well about 2weeks after our daughter turned one, i found out i was pregnant again. I was only 4weeks though. So i pretty much waited till my daughter was 12months before i got pregnant again. How safe is it for me to try a Vbac at this point? I really want to do one rather them cut me.open again enless i really had to.

  • Tara

    Hi, would there be any evidence that the longer the interval between pregnancies, the lower the risk of uterine rupture. By longer, I mean several years as opposed to 18 months. There will be over 5 years between my two deliveries, will this work in my favour? Many thanks.

  • Amy

    i am looking to VBAC 13.5 months after my csection. Too risky???

    • Jen Kamel

      Amy,

      There might be an elevated risk, but with the small studies we have on birth intervals that don’t control for important factors like labor induction and augmentation, it’s hard to quantify how much of a higher risk. What does your doctor/midwife say?

      Best,

      Jen

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